• Version
• 200 Downloads
• 1.08 MB File Size
• 1 File Count
• November 2, 2016 Create Date
• November 2, 2016 Last Updated

National Advisory Committee for Aeronautics, Report - Linearized Lifting Surface and Lifting Line Evaluations of Sidewash Behind Rolling Triangular Wings at Supersonic

The lifting-surface sidewash behind rolling triangular wings
has been derived for a range of supersonic Mach numbers for
which the wing leading edges remain swept behind the Mach
cone emanating from the wing apex. Variations of the side—
wash with longitudinal distance in the vertical plane of sym-
metry are presented in graphical form.

An approximate expression for the sidewash has been devel—
oped by means of an approach using a horseshoeavm'tex approxi-
mate-lifting—line theory. By use of this approximate expres-
sion, sidewash may be computed for wings of arbitrary plan
form and span loading. A comparison of the sidewash com-
puted by lifting-surface and lifting-line expressions for the
triangular wing showed good agreement except in the vicinity of
the trailing edge when the leading edge approached the sonic
condition.

An illustrative calculation has been made of the force induced
by the wing sidewash on a vertical tail located in various longi-
tudinal positions.

In order to make reliable estimates of the total forces and
moments acting on an aircraft, accurate evaluations are
required of the loadings on the individual isolated compo-
nents and of the interference eflfects between components.
Although considerable efiort has been expended in recent
years to supply much of this needed information for the
supersonic speed range, many important problems remain.
Among these is the induced efiect of the wing flow field or,
more precisely, the wing sidewash on the vertical tail. The
only specific numerical results of this nature obtained to
date have been for the angle-of-attack motion. In the
vertical plane of symmetry for this case, however, the side—
wash is zero and tail surfaces located in this plane are un—
affected. This is not the situation for the rolling, yawing,
and sideslipping motions where the sidewash in the vertical
plane of symmetry is finite and the load induced on the
vertical tail can be appreciable. Evaluation of the sidewash
for these motions would, therefore, be important in the
prediction of the lateral stability of supersonic aircraft.